Regulating apparatus for electric furnaces.



W. SYKES.

REGULATING APPARATUS FOR ELECTRIC FURNACES.

APPLICATION FILED APR. I2, 1912.

Patented Oct. 2, 1917.

3 SHEETS-SHEET I.

24 ZPL R O T N E V N WITNESSES l ATT'ORNEY w. sYKEs. REGULATTNGAPPARATUS FOR ELECTRIC FURNACES.

APPLICATION FILED APR. l2. 1912.

Patented Oct. 2, 1917.

3 SHEETS-SHEET 2.

INVENTOR 5ATTRNEY W. SYKES. REGULATING APPARATUS Fon ELECTRIC Fu-RNACES.

APPLICATION FILED APR. l2. |932.

Patented Oct. 2, 1917.

3 SHEETS-SHEET 3.

WITNESSES: IN EN OR TTRN EY UNITED STATES PATENT oEEioE.

WILFRED SYKES, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

REGULATING APPARATUS FOR ELECTRIC FURNACES.

Specification of Letters Patent.

Patented Oct. 2, 1917.

To all whom it may concern:

Be it known that I, WILFRED Simms, a subject of the King of GreatBritain, and a resident of Pittsburgh, in the county of A1- legheny andState of Pennsylvania, have invented a new and useful Improvement inRegulating Apparatus for Electric Furnaces, of which the following is aspecification.

My invention relates to electric furnaces and it has special referenceto such furnaces as are provided with movable electrodes.

The object of my invention is to provide a simple and durable means forautomatically eilecting and maintaining the most advantageous positionfor the movable electrode of a furnace of the character above specifiedduring the entire life of the e1ectrode.

Electric furnaces of the Hercult and Girod ty es, in which an electricarc is utilized flir producin heat, are equipped with vertically mova leelectrodes which are frequently very large and heavy. In a large furnaceof this character, a single electrode may weigh from two to threethousand pounds.

The above mentioned electrodes are adjusted by some suitable means whichare operated either by individual driving motors or in oups by a singlemotor, clutches be ing utilized for independently operating theelectrodes with the latter arrangement.

In order to secure the best results in operation, the position of themovable electrode must be constantly adjusted, and the usual methods ofregulating these members have not been entirely satisfactory.

According to my present invention, I not only provide for the automaticadjustment of movable electrodes in response to the current traversingthe arcs which are maintained in electric furnaces, but I alsocompensate for the variations in weight of the electrodes that arecaused by their gradual consumption in service.

Figure 1 of the accompanying drawings, is a diagrammatic view of anelectric furnace and its regulating apparatus arranged in accordancewith my invention. Fig. 2 is a view, corresponding to Fig. 1, of aslightly modified system of furnace regulation embodying my invention.Figs. 3 and 4 are detail views illustrating modified compensatingdevices which may be substituted for the compensating apparatus of Fig.1.

Fig. 5 is a view, corresponding to Fi 1 and 2., of another arrangementemboy ing my invention. Fig. 6 is a detail view of the compensatingapparatus employed in the arrangement of Fig. 5, and Figs. 7 and 8 areviews, corresponding to Fig. 1, of o ther arrangements embodying myinvention. Fig. 9 is an elevation of the compensatin mechanism of Fig.8.

Re eri-ing to Fig. 1 of the drawings, a furnace receptacle 1 ispartially filled with ore 2, or other material to be reduced, which is.electrically connected to a supply circuit conductor 3 by means of aconductor 4. A movable electrode 5 is preferably suspended verticallyabove the furnace receptacle 1 into which its lower end extends. Theelectrode 5 is connected to a supply circuit conductoi 6 by means of aconductor 7.

The electrode 5 is largely supported by a counter-weight 8 to which itis operatively connected by cables or chains 9 and 11 and drums 10 and12. The drum 10, upon which one end of the chain or cable 9 is wound, iscylindrical in form but the drum 12 is frusto-conical in order tocompensate, as hereinafter pointed out, for variations in the weight ofthe electrode. The cable or chain 11 issecured to the electrode, extendsover sheaves 13 and 14 and is wound upon the frusto-conical drum 12.

The drums 10 and 12- are both lsecured to the Shaft 15 of a motor 16which is so controlled as to effect a rotative movement of the drums 10and 12 in the one direction or the other, in response to variations inthe current supplied to the furnace. The arrangement of parts is suchthat rotation of the motor 16 in the one direction winds the cord orchain 11 upon the drum-12 and raises the electrode 5, while rotation ofthe motor in the opposite direction pays out the cable or chain 11 andlowers the electrode 5.

Relatively small rotative movements of the drums are required toproperly regulate the position of the electrode during any short periodof time, but, by reason of the fact that the electrode 5 is graduallyconsumed in operation, the neutral position of 105 the drums about whichthe aforesaid small adjustments take place, is constantly changing. Thesurface of the frusto-conical drum `slsting lows:

12 is so proportioned that the torque produced by the weight 8 onthe-shaft is always substantially counteracted. by .the torque exertedby the electrode 5. 1

The motor 16 1s, therefore, only called upon to exert a small continuoustorque asthe conterweight and-to eect the aforesaid small rotativeadjustments of the drum in order to maintain a substantially constantarc in the ace.

The motor 16 is a two-phase induction motor and has two airs ofterminals 17 and 21 to which secon ary windings 18 and 22 oftransformers 19 and 23 are respectlvely connected. The primary windings20 and 24' of the transformers 19 and 23 are respectively connectedacross one phase of the sugly circuit and in a series relation with t efurnace arc.

The operation of the apparatus is as fol- The motor 16 is so andproporltioned as to exert a continuous torque upon the shaft 15 whichassists the weight 8 and tends to raise the electrode 5. When apredetermined` current traverses the furnace arc and the seriestransformer winding 24, the parts are in equilibrium, the torque exertedby the motor being then equal to the difference between the torqueexerted by the electrode 5 and the weight 8. The torque of the motorvaries as the current traversing the furnace arc, and the arrangement issuch as to maintain this current substantially uniform. For instance, asthe electrode 5 consumes, the distance between it and the moltenmaterial 2 increases, with the result that the current traversing thearc decreases due to the lengthening of the arc. The torque of themotor, therefore, decreases, and the weight of the electrode overpowersthe combined torques exerted by the weight 8 and the motor. Theelectrode is thus lowered until the current is restored to the valuewhich it is desired to maintain nearly uniform. On the other hand, if,for any reason, the current ofthe arc increases unduly, the torque ofthe motor increases correspondingly and, acting with the weight 8,raises.

As the electrode 5 is consumed, a greater length of the cableor chain 11is paid off of the drum 12 and, consequently, by reason of the conicalshape of the drum 12, the radius of the point of application of theforces exerted by the electrode upon the drum, is increased. It is,therefore, evident that the electrode may exert a constant torqu'e onthe shaft 15, although it is continuously being consumed and its weightgradually reduced.

The mechanical arrangement and design of the parts shown in Fig. 2 isthe same as `\tha.t shown in Fig. 1, and' corresponding parts aredesignated by the same reference characters. The weight 8 of Fig. 2,however, slightly overbalancesthe weight of the electrode 5 and thetorque exerted .by the motor 16 tends to -raise the weight and lower theelectrode.

The windings of the motor 16 are respectively connected in shuntrelation to the -furnace arc, and to the terminals of a voltagetransformer 25, which corresponds to the transformer 19 of Fig. l. Theoperation of this arrangement is as follows:

A condition of equilibrium is established when the torque exerted by themotor 16, added to the torque exerted by the electrode 5, is equal andopposite to the torque exerted by the weight 8. If, under theseconditions, there is an increase in the voltage or tbe electromotiveforce dro across the furnace arc, the torque exerted y thev motor 16will be increased and will produce such a rotative movement of the drums10 and 12 as to lower the electrode. Conversely, if the voltage o'r theelectromotive drop across the furnace. are decreases, the torque exertedby the motor 16 will be diminished and the weight 8 will overhaul theelectrode and raise it until conditions of equilibrium are restored.

The drums 10 and 12 in the arrangements of Figs. 1 and 2, constitutewhat I shall term the compensating mechanism, but other structures anddevices for accomplishing the same purpose may be substituted, forexample: In Fig. 3 a single frusto-conical drum 26 is substituted forthe drums 10 and 12, both of the cables or chains 11 and 9 being securedto it and wound upon it.

The arrangement of parts is such that, as the electrode is consumed andthe cable or chain 11 is paid out, the point of application of the forceexerted through the cable or chain -11 will be further removed from thecenter, while the same movement of the drum will gather a larger portionof the cable or chain 9, and the point of application of the forceexerted by the weight 8 will be located at a lpoint nearer the center.By this means, the torques exerted by the electrode and the weight areboth dlminished but are maintained equal.

In Fig. 4, a drum 27, corresponding to the drum 12, is substituted forthe drum 10, and a drum 28, corresponding to the drum 10, is substitutedfor the drum 12. With this arrangement, the torque of the weight isdiminished by the gradual shifting of the point of application of theforce which it exerts upon the drum 27 to correspond to the decrease intorque exerted' by the electrode as its weight is diminished.

Referring to Figs. 5 and 6 of the drawings, the furnace reptacle 29 hereshown, is provided with an electrode 30, having a rack projection 31with which a driving pinion 32 coperates. The pinion is secured to theshaft of a n xptor which is adapted to adjust the position of theelectrode. A large portion of the Weight of the electrode iscounterbalanced by a weight 34 to which it is connected by a cable orchain 35.

The' motor corresponds to the motor 16 of Fig. 1 and is correspondinglyenergized, so that it exerts a continuous torque tending to assist theweight in raising the electrode.

The cable or chain 35 extends over a sheave or pulley 36 and ispreferably divided aud wound upon a frusto-conical drum 37 to which theends of the divided cord are secured.

The form of the drum and the manner in which the cable ends are woundupon it are clearly shown in Fig. 6.

The arrangement of parts is such that the reduction in weight of theelectrode is compensated for in a manner corresponding to that of thearrangement of Fig. 3.

Referring to Fig. 7, the arrangement of parts is similar in all respectsto that of Fig. 1, and corresponding parts are designated by the samereference characters. The furnace, however, is supplied with energy froma single-,phase sourceof energy (not shown) through conductors 38 and 39and an adjustable reactance 40 is connected in circuit with one of themotor windings in order to secure a displacement of phase. The operationof the system is the same as that of Fig. l.

When it is desired to govern the positions of one or more inclinedelectrodes 41, as illustrated in Fig. 8 of the drawings, the frictionbetween each electrode and its support 42 may be suiiciently great toprevent a free downward movement of the electrode by the attraction ofgravity. In this case a rack projection 43, corresponding to theprojection 31 of Fig. 5, is provided to mesh with a pinion 44 which isdriven by an electric motor 45. A frusto-conical drum 46 is secured tothe motor shaft 47 and a weight 48 is suspended from a cord or chain 49which is wrapped about the drum 46 and is secured to it.

The cord or chain 49 is so wrapped or wound upon the drum as to tend todrive the motor shaft in such direction as to move the electrode 41downwardly. The motor connections are such as to oppose the torqueproduced by the weight 48. The drum 46 is so shaped as to compensate forthe decrease in weight of the electrode by reason of its naturalconsumption in operation. The operation ofthe system of Figs. 8 and 9corresponds to that of Fig. 5.

It is evident that any of the compensating mechanisms illustrated may beadapted for use with any one of the arrangements shown, and thatelectric motors of other types may be substituted for -thoseillustrated.

I claim as my invention:

1. The combination with a pair of cooperating relatively movablemembers, one of which is gradually consumed, of means for compensatingfor the variations of weight in the member which is consumed, and meanscomprising said compensating means for automatically maintaining apredetermined relation between said members.

2. In an electric furnace, the combination with a movable electrode, acounterweight and an interposed rotatable member so formed as tocompensate for the variations in weight of the electrode, of anautomatic means for producing rotative movements of the rotatablemember.

3. In an electric arc furnace, the combination with a movable electrode,a counterweight and an interposed rotatable member so formed as tocompensate for the variations in weight of the electrode, of automaticmeans dependent upon the current traversing the arc for producingrotative movements of the rotatable member.

4. The combination with an electric furnace having a consumableelectrode, of means for compensating for variations in the weight of theelectrode as it is consumed, and means comprising said compensatingmeans for automatically regulating the position of the said electroderelatively to the remainder of the furnace in accordance with variationsof an electrical condi-tion within the furnace.

5. The combination with an electric furnace having a consumableelectrode, of means for compensating for variations in the weight ofsaid electrode, and an electric motor for automatically varying theposition of the electrode relatively to the remainder of the furnace,the said motor being supplied with current that is dependent in valueupon the current traversing the furnace arc.

6. The combination with an electric fur nace having a consumableelectrode, of means for compensating for variations in the weight ofsaid electrode as it is consumed, and an electric motor forautomatically varying the position of the electrode relatively to theremainder of the furnace, the said motor being supplied with currentproportional to that supplied to the furnace.

7. The combination with an electric furnace having a consumableelectrode, and a counterweight therefor, of means for compensating forvariations in the weight of the electrode as it is consumed, an electricmotor for varying the position of the electrode relatively to theremainder of the furnace, and means for automatically con-trolling thesaid motor in accordance with varior variations in the wei ht of lingthe said motor in accordance with variations in the amount of currenttraversing the furnace arc.

In testimony whereof, I have hereunto subscribed lmy name this 5th dayof April, 15

' WILFRED SYKES. Witnesses: B. B. Hnms, MJC. MEnz.

